The silviculture of dipterocarp trees in Sarawak Malaysia 2: improvement felling in primary forest stands

Primack R.B., . and Chai E.O.K., . and Tan S.S., . and Lee H.S., . The silviculture of dipterocarp trees in Sarawak Malaysia 2: improvement felling in primary forest stands. pp. 43-61. ISSN 0302-2935

Improvement Felling was utilized to free the canopies of dipterocarp trees growing in six lowland primary forest plots in Sarawak. The studies were initiated between 1935 and 1955 and were followed for as long as twenty years. Mean diameter increments are not demonstrably higher following improvement Felling in comparison with trees growing in primary forest though variation in site characteristics initial size distribution and species composition may obscure any silvicultural effects. Longterm patterns of annual diameter increment are dominated by a striking three- to six- year cycle of rapid growth followed by slow growth. Years of low growth can often be correlated with years of flower and fruit production. We do not know if growth and reproduction are directly related or are controlled by some environmental factors such as drought stress. In two of the forests there is a decline in growth rates over the twenty years of study but this is not seen in the other forests. Evaluation of these Improvement Felling plots is problematic because the plots were set up without experimental controls for comparison. Conclusive evidence on the effectiveness of Improvement Felling for increasing timber production in primary lowland forest in Sarawak will come only from properly designed long-term block experiments.

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Abstract

Improvement Felling was utilized to free the canopies of dipterocarp trees growing in six lowland primary forest plots in Sarawak. The studies were initiated between 1935 and 1955 and were followed for as long as twenty years. Mean diameter increments are not demonstrably higher following improvement Felling in comparison with trees growing in primary forest though variation in site characteristics initial size distribution and species composition may obscure any silvicultural effects. Longterm patterns of annual diameter increment are dominated by a striking three- to six- year cycle of rapid growth followed by slow growth. Years of low growth can often be correlated with years of flower and fruit production. We do not know if growth and reproduction are directly related or are controlled by some environmental factors such as drought stress. In two of the forests there is a decline in growth rates over the twenty years of study but this is not seen in the other forests. Evaluation of these Improvement Felling plots is problematic because the plots were set up without experimental controls for comparison. Conclusive evidence on the effectiveness of Improvement Felling for increasing timber production in primary lowland forest in Sarawak will come only from properly designed long-term block experiments.

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Item Type:	Article
Additional Information:	6 graphs; 1 table; 15 ref. Summary (En)
AGROVOC Term:	SHOREA
AGROVOC Term:	DRYOBALANOPS
AGROVOC Term:	DIPTEROCARPUS
AGROVOC Term:	SARAWAK/ DIAMETRO
AGROVOC Term:	CORTA
AGROVOC Term:	MEJORAMIENTO DEL RODAL
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:55
URI:	http://webagris.upm.edu.my/id/eprint/20172

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